Prognostic Meteorological Discussion
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FXAK02 KWNH 231900
PMDAK

ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
159 PM EST SUN NOV 23 2014

VALID 12Z THU NOV 27 2014 - 12Z MON DEC 01 2014

THE MEDIUM RANGE FORECAST CHALLENGE---TROUGH DISPERSION IN THE
BERING SEA AND ITS GRADUAL EASTWARD MIGRATION ACROSS THE ALEUTIANS
AND INTO A POSITION BY DAY 8---THAT REMAINS NEARER TO ITS `CLIMO`
POSITION ALONG 150W LONGITUDE FOR LATE NOVEMBER.

PRIOR TO ITS MIGRATION INTO THE PACIFIC/WESTERN GULF OF
ALASKA...THERE ARE SEVERAL SHORTWAVES THAT ROTATE
COUNTER-CLOCKWISE ACROSS THE BERING SEA AND BRUSH THE YUKON DELTA
BEFORE MIGRATING WESTWARD INTO THE WEST CENTRAL BERING SEA. ON
SATELLITE...THE PRIMARY IMPULSE TO BE CONCERNED WITH---IS
CURRENTLY LOCATED INVOF BETWEEN 30N-40N ALONG 160E. IT`S MIGRATION
EASTWARD---INCORPORATION INTO THE POLAR WESTERLIES---INFUSION INTO
THE UPPER-LEVEL TROUGH IN THE BERING SEA---AND/OR EJECTION FROM
IT---WILL BE A WEATHER FEATURE FOR THE BERING SEA AND EASTERN
PACIFIC AT DAY 4.

THE 23/00Z AND 23/12Z DETERMINISTIC GUIDANCE SPREAD IN THE BERING
SEA REMAINS VERY LARGE---YET THE ECENS/GEFS MEANS AGREE ON A VERY
GRADUAL EASTWARD DRIFT OF THE BROAD CYCLONIC FLOW THROUGH TIME.
THE 500MB FORECASTS LEAVE ROOM FOR THE NORTHERN STREAM---IN
NORTHEAST SIBERIA---TO INTRODUCE A SERIES OF MID-LEVEL WAVES AND
ENERGY INTO THE BERING SEA CYCLONE/TROUGH FOR DAYS 4-5. THIS
NORTHERN STREAM AND A MID-LATITUDE WESTERLY PACIFIC JET
ORIGINATING OVER JAPAN/KOREA SHOULD CONTINUE TO KEEP A SERIES OF
MID-LEVEL WAVES SHEARING OUT AT LOWER LATITUDE...AND GRADUALLY
BEGIN TO DRIFT THE BULK OF THE BERING LOW EASTWARD---ACROSS THE
EASTERN ALEUTIANS---ON/AFTER DAY 6. TO THE NORTH OF THIS LOW`S
TRACK...COLD/DRY WEATHER IS ANTICIPATED FOR MUCH OF INTERIOR
ALASKA. FOR DAYS 7-8...THE FLOW PATTERN ALOFT IN THE NORTH PACIFIC
REMAINS ESSENTIALLY...FAST-ZONAL WESTERLY (INVOF 110KTS) BETWEEN
40N-45N WITH VERY LITTLE AMPLITUDE. THIS SHOULD MAINTAIN A STORM
TRACK THAT MOVES RAPIDLY ACROSS THE EXTREME SOUTHERN GULF OF
ALASKA---AND KEEP THE SOUTH COAST FREE OF DEEP CYCLONES.
VOJTESAK

$$




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